Circular knitting machines are widely used now in the textile industry. Many new types of circular knitting machines have been developed to increase operation efficiency and enrich function. These days there are circular knitting machines that can change yarns to alter colors and patterns of the fabrics. This is accomplished by altering different color of yarns on the needles. Each time the yarn of one color is changed, the original yarn has to be cut off, and another color of yarn is used to continue knitting operation. If the debris of the cut off yarn is not properly handled and scatters, it could be gathered in the fabric and form small patches of motley patterns. To remove the yarn debris takes a great deal of extra labor and time.
To remedy the aforesaid problem, R.O.C. patent publication No. 182863 discloses a technique which has an air duct extended from the interior of a circular knitting machine to connect to a suction machine located outside the knitting machine. It has to provide an extra blower outside the knitting machine to generate suction force. As the air duct is extended from the interior of the knitting machine to the blower, the air duct is too long and bent and twisted. As a result the suction force decreases. And yarn debris and flints tend to accumulate in the duct and result in clogging. Utilization efficiency suffers. R.O.C. patent publication No. 517722 discloses another technique which has a blower to generate airflow to prevent yarn flints and debris depositing on the knitting machine. It also has a lengthy duct that weakens the airflow. Hence a powerful blower has to be used. The cost is higher and maintenance is more difficult. All the conventional techniques still leave a lot to be desired. There are still rooms for improvement.